Rubber band motors are used to power many things, toys--especially model airplanes--being among the more common things. However, rubber band motors have more uses than model airplanes. For example, among the toys, they may power almost any vehicle, such as model autos, boats, and the like.
A common problem with rubber band motors is that they must first be wound to store energy. In the simplest motors, this means turning a propeller, or the like, with a finger which is a time consuming and boring chore. Another winding device is a separate unit, such as a small hand drill, which may be hooked to the propeller. Then, a hand crank or wheel is turned to rotate the propeller and store energy in the rubber band. However, this use of a separate unit requires one to carry and hook together more parts, and often requires two people, one to hold the model airplane and the other to hold the unit and turn the crank.
Hence, a desirable rubber band motor requires something which is fast operating, which does not require extra parts, and which may be used by a single person. This, in turn, means that it must be extremely lightweight since a model airplane powered by a rubber band motor does not have the energy to lift much weight.